Shielded transducer having means to reduce core movement

Claim 1

AN ACTUATOR COMPRISING, A CYLINDER HAVING CLOSED ENDS, A PISTON RECIPROCABLE IN SAID CYLINDER AND HAVING A ROD PROJECTING THROUGH ONE END THEREOF SAID PISTON DEFINING IN COMBINATION WITH THE CLOSED ENDED CYLINDER, EXPANSIBLE PRESSURIZATION CHAMBERS ON OPPOSITE SIDES OF THE PISTON, SAID CYLINDER HAVING PORTS FOR THE ALTERNATE INTRODUCTION OF PRESSURIZED FLUID INTO THE PRESSURIZATION CHAMBERS AT THE OPPOSITE END PORTIONS OF THE PISTON TO RECIPROCATE SAID PISTON AND ROD, A TRANSDUCER DISPOSED IN THE PRESSURIZATION CHAMBER AT THE END PORTION OF SAID CYLINDER OPPOSITE SAID ROD, AND EXPOSED TO THE FLUID INTRODUCED THEREIN, SAID TRANSDUCER COMPRISING A COIL HAVING ELECTRICAL LEADS EXTENDING FROM SAID ACTUATOR AND A CORE DISPLACEABLE WITHIN SAID COIL TO PRODUCE AN OUTPUT SIGNAL THEREFROM WHICH IS A FUNCTION OF THE RELATIVE POSITION OF SAID CORE WITHIN SAID COIL, AND POSITIVE COUPLING MEANS FOR CONNECTING SAID CORE AND PISTON AND POSITIVELY DISPLACING SAID CORE IN RESPONSE TO PISTON MOVEMENT AT A FIXED LESSER RATE THAN SAID PISTON MOVEMENT, WHEREBY A RELATIVELY SMALL TRANSDUCER MAY PROVIDE AN OUTPUT SIGNAL REFLECTING THE FULL RANGE OF A RELATIVELY LONG PISTON STROKE.